(none) - 2

Thank you for the clarification.

If you drop out of the top 3, you lose the right to challenge the top 1 and 2. If you break into the top 3, you gain the right to challenge. The top 3 is dynamic.

The need for this condition is due to the problem of a top 1 player not wanting to play at all in the last week, maintaining an incredibly high rating.

Again, if you break into the top 3, you challenge higher-ranked players, but for some reason, they don't have time to play with you, or they postpone it, and after a couple of days, player 4 or 5 overtakes you, and they tell you that they are no longer obligated to play with you until you regain your position. There will be many ways to avoid playing, and then there will be arguments about who didn't fulfill the conditions and why.
A fixed Olympic-style system would be easier for you as organizers, and the value of such games would increase many times over.
In any case, respect for these competitions for the top 1 ranking.